NEW YORK (Reuters Health)
— Short bursts of intense
exercise before meals may help control blood sugar spikes better than
one longer, less intense session, suggests a new small study.

Researchers say these “exercise snacks” may be an
effective way to improve blood sugar control among people with
insulin resistance, a precursor to diabetes.

“Exercise spread across the day reduces sedentary time, and spread
before meals reduces blood glucose spikes after meals,” said lead
author Monique Francois.

“Exercise on top of an active lifestyle needs to be more intense
than we normally do when walking or moving around,” Francois, from
the University of Otago in Dunedin, New Zealand, added in an email
to Reuters Health.

She explained that exercise, along with insulin, stimulates muscles
to take up glucose from the blood.

“Moving glucose into the muscle so it can be used as fuel or stored
lowers blood glucose, as the body only wants a certain amount of
glucose in the blood.”

Francois and her colleagues studied two women and seven men
diagnosed with insulin resistance. Two of the participants had type
2 diabetes, but none were taking medication for diabetes or blood
sugar control.

The participants completed three separate one-day exercise programs
in a random order.

The exercise snacks program involved short bouts of intense exercise
on a treadmill before breakfast, lunch and dinner. The composite
exercise snacks regimen was similar, but included some resistance
exercises alternating with walking. The traditional continuous
exercise program consisted of 30 minutes of moderate-intensity
walking before dinner only.

Meal timing and composition were the same during the three days.

The researchers found that the exercise snacks and composite
exercise snacks routines controlled blood sugar more effectively
than the continuous exercise routine.

Specifically, there was a 17 percent reduction in glucose levels
over the three hours following breakfast and a 13 percent reduction
in glucose levels after dinner on the exercise snack days compared
to the continuous exercise days.

Across the day this represented a 12 percent reduction in average
post-meal blood glucose levels, the authors report in the journal
Diabetologia.

This was a small study and more long-term studies need to be done to
confirm the results. Francois said she’d also like to learn more
about the best time for exercising and how to encourage people to
exercise more.

She said high-intensity exercise can be performed in about half the
time with similar or greater benefits than low- to
moderate-intensity exercise.

“In this study interval exercise using walking uphill or resistance
band exercises both improved glucose control similarly - the
combination of resistance exercise to exercise the upper body and
uphill walking targeting the lower body was chosen to maximize the
muscle mass used,” she said.

Francois added that cycling, walking and team sports have all been
proven to be effective in helping to control blood sugar levels.

Colberg-Ochs studies diabetes and exercise at Old Dominion
University in Norfolk, Virginia. She wasn’t involved with the new
research.

“My main issue with high-intensity intervals like that is that many
people with diabetes (not just pre-diabetes, or insulin resistance)
really aren't in any physical shape to undertake that type of
exercise, and many of them have undiagnosed (or diagnosed)
cardiovascular problems that may make such exercise unsafe for them
to undertake as well,” she said.

It's a risky activity for those patients that doctors would most
want to help, Colberg-Ochs said.

“I would suggest instead that the walking be undertaken after eating
to have a greater effect at suppressing post-meal rises in blood
glucose levels, in case some individuals cannot undertake the
‘exercise snacks,’” she said.